Recently in a medical spot, diagnosis using an imaging diagnostic system (hereinafter called a modality) represented by an X-ray computerized tomograph (X-ray CT), an ultrasonic diagnostic system and a magnetic resonance imaging (MRI) system is frequently performed. Further currently, computer aided detection (CAD) using these is also frequently used (for example, refer to JP-3083606).
The computer aided diagnostic system is a system for automatically extracting sick portions and outputting the features of normal and abnormal patterns to aid diagnosis by a doctor for interpreting a shadow. It automates detection work by programming a diagnostic rule by the doctor for interpreting a shadow and reduces a load of the doctor for interpreting a shadow. The doctor for interpreting a shadow finally classifies whether a detected sick portion is a tumor or not or whether it is benign or malignant based upon the output result. Computer aided diagnosis including this classification in the computer aided detection described above is also called CAD.
For the object of such computer aided detection, in addition to automatic diagnosis and labor saving in screening, it can be given to prevent oversight by a doctor. A conventional type radioscopic method in X-ray direct photography and an X-ray TV apparatus has a defect that as information is integrated in a direction of the thickness, contrast is hardly acquired and even if there is a fault, its position in the direction of the thickness cannot be known. For example, a tumor located at the back of the heart and a tumor located at the apex of a lung are difficult to discover in the above-mentioned radioscopic method. In the meantime, also in X-ray CT without such a defect, some tumors may look like a blood vessel at a glance and there may be unexpected oversight.
For such oversight, as CAD is basically acquired by programming a diagnostic rule of a doctor for interpreting a shadow, the similar oversight is estimated even according to CAD.
To prevent such oversight, a system for comparing the result of CAD and a report on the interpretation of a shadow by a doctor and issuing warning in case there is difference between both (for example, refer to JP-3085724) and a system for enhancing the precision of diagnosis by comparing the current image and a past image (for example, refer to JP-A-2001-137230) are proposed.
To prevent such oversight and to enhance the reliability of diagnosis based upon an image, a double check by comparing images acquired in plural systems is more desirable. However, this imposes a double load on a doctor for interpreting a shadow. Besides, at least two types of images are required to be compared, however, two types of results of diagnosis are not always acquired.
The invention is made in view of the above-mentioned situation and the object is to provide a computer aided diagnostic system that enhances the reliability of diagnosis based upon an image and does not impose an excess load on a doctor for interpreting a shadow.
Another object of the invention is to provide a computer aided diagnostic system provided with a function for enabling diagnosis of two types based upon only an image for medical application acquired in one modality.